1. Field of the Invention
This invention pertains generally to the field of cockpit indicators or display units that provide flight information to the pilot or flight crew of an aircraft, and more particularly to synthetic vision systems (SVS) or enhanced vision systems (EVS).
2. Description of the Related Art
Modern avionics systems employ Head-Down Display (“HDD”) and Head-Up Display (“HUD”) systems for providing tactical flight information to the pilot. In an HDD system, a tactical flight display is mounted in the cockpit instrument panel directly in front of the pilot and below windshield level. To view the presentation of information on a display unit of an HDD system, a pilot must look down into the cockpit, causing him or her to take his or her eyes from the outside scene in front of the aircraft. In a HUD system, a HUD unit is mounted in front of the pilot at windshield level and is directly in the pilot's field of vision. The HUD system is advantageous because the display is transparent allowing the pilot to keep his or her eyes “outside the cockpit” while the display unit provides tactical flight information to the pilot.
Modern avionics systems may employ Synthetic Vision Systems (“SVS”) and Enhanced Vision Systems (“EVS”) for displaying terrain information to both HDD and HUD systems. The SVS and EVS systems are advantageous because they present terrain information and objects of a scene outside the aircraft to the pilot. For example, an airport, airport runways, navigation aids, and obstacles may be objects displayed by an SVS that can increase a pilot's Situational Awareness and potentially provide a means for navigation. While the presentation of this information is advantageous to the pilot, there are times when the depiction of object information could obstruct or obscure a pilot's view of tactical flight information or symbology simultaneously depicted. Airports can vary in size and can be, at times, difficult to identify with the simultaneous display of flight symbology and a three-dimensional perspective of terrain. This difficulty of identification is especially acute when an airport or another object is relatively distant from the current position of the aircraft and appears relatively small due to the three-dimensional minification of distant objects.